This page is Ready to Use

Notice: The WebPlatform project, supported by various stewards between 2012 and 2015, has been discontinued. This site is now available on github.

reserved words


Reserved words are words that you cannot use as identifiers in JavaScript.



JavaScript has a number of reserved words that you cannot use as identifiers. Reserved words have a specific meaning to the JavaScript language, as they are part of the language syntax. Using a reserved word causes a compilation error when loading your script.


Future reserved words

JavaScript also has a list of future reserved words. These words are not currently part of the JavaScript language, although they are reserved for future use. For more information about future reserved keywords in JavaScript, see JavaScript Future Reserved Words.

Intrinsic objects or functions

When choosing identifiers it is also important to avoid any words that are already the names of intrinsic JavaScript objects or functions, such as String or parseInt.

Reserved Keywords

  • break
  • case
  • catch
  • continue
  • debugger
  • default
  • delete
  • do
  • else
  • finally
  • for
  • function
  • if
  • in
  • instanceof
  • new
  • return
  • switch
  • this
  • throw
  • try
  • typeof
  • var
  • void
  • while
  • with
  • yield

See also

Other articles

JavaScript Future Reserved Words


  • Microsoft Developer Network: Article